Design and analysis of 1–10GHz band selected bandpass filter with broad tunable range

Abstract

The application of Microstrip technology offers us a very compact realization of the designed filter resulting in reduced filter size and improved output. In this paper we propose a capacitor and varactor tuned microstrip coupled bandpass filter (BPF) loaded with parallel coupled microstrip line with varactor diodes and capacitors to enhance tuning of the bandpass filter. This configuration helps in enabling the tunability of the designed BPF by varying the values of the varactors and capacitances inserted in the circuit. With the variations, a wide tuning range can be obtained by employing low capacitance values and varactor values with which a tunable bandpass filter can be achieved. Based on the requirement of the operating frequency the bandpass filter can be tuned for the particular frequency thereby enhancing the band selectivity character in the proposed design. Before the construction of the filter in ADS the theoretical analysis for the filter to be designed are worked out to obtain the mathematical values of the microstrip lines. The obtained simulated results of the BPF show a tuning range (between 1-10 GHz). The proposed design has a advantage of producing better performance. Most of the common applications of filters are within the 1.0 to 10 GHz range, the designed microstrip bandpass filters find its applications in the operating of various communications. The various microwave bands in which the proposed filter design are L band, S band, L band, X band, Ku band.